Response Of Wheat Cultivars Research Articles

Differences in Wheat Cultivar Response to Nitrogen Supply. II: Differences in N‐Metabolism‐Related Traits

AbstractTwo‐year field trials with winter wheat cultivars Batis and Toronto were conducted in Southern Bavaria, Germany, to investigate the possible causes of cultivar differences in response to N supply varying in total amount and time of application. The results revealed cultivar‐related differences in response to N fertilization in all parameters included in this study. Amount and timing of N fertilization was a strong indicator of N uptake into canopies and three phases of cultivar differentiation became apparent. Cultivar differences in N content were most clearly expressed during early growth stages, but distinctive differences in canopy N uptake were observed during later growth stages. Nitrate reductase activity, water‐soluble carbohydrates (WSC), and plant nitrate content varied in response to N supply within cultivar‐specific patterns that included reversals in cultivar ranking during canopy development, and provided additional indications for elevated intensity of N metabolism in cv. Toronto when compared with cv. Batis. Apart from such differences Batis partially compensated for delayed N uptake in earlier phases during the latter part of grain filling, presumably due to differences in root system development. Cultivar differences in regression of tillering, stand density, grains per ear and grain density (grains m−2) on a number of N metabolism‐related parameters have been determined. They contribute considerably to the understanding of cultivar differences in grain yield components, as presented in an earlier communication. For 1000 grain weight, least affected from N supply within each year, large differences between years seemed to relate to differences in WSC content observed between heading and flowering, whereas cultivar differences in the level of grain N content and reaction to N supply were more directly determined by differences in N uptake and remobilization, and possibly enhanced by sink limitations of Toronto in grain size development.

Soft Red Winter Wheat Cultivar Response to Tillage in the Mid-Atlantic Coastal Plain

Current cropping systems in the Mid-Atlantic Coastal Plain utilize no-tillage seeding methods for corn and soybean, but no-tillage small grain acreage is also increasing in this region. The objectives of this research were to evaluate soft red winter wheat cultivars for grain yield, test weight, and lodging across three tillage systems in the Mid-Atlantic Coastal Plain. Five soft red winter wheat cultivars were grown under no-tillage, reduced tillage, and conventional tillage in the Coastal Plain of Virginia from 2002-2004. Grain yields for the site averaged 80, 60, and 71 bu/acre in 2002, 2003, and 2004, respectively. Grain yield and test weight was effected by tillage treatment only in 2002 when the lower yields and test weights under conventional tillage were likely due to a higher degree of lodging. There was no consistent influence of tillage treatment on any variety. High-yielding cultivars performed similarly under conventional, reduced, and no-tillage systems. Cultivar recommendations for the region should not be made separately on the basis of tillage system.

Comparative Tissue Culture Response of Wheat Cultivars and Evaluation of Regenerated Plants

Comparative Tissue Culture Response of Wheat Cultivars and Evaluation of Regenerated Plants

Ion distribution in wheat cultivars in response to salinity stress

In a pot experiment, 30 cultivars of wheat ( Triticum aestivum L.) were evaluated in terms of their leaf and grain K/Na ratios and their ion selectivity responses to NaCl salinity. A completely randomized block design with factorial treatments in three replications was employed. Tap water, both with and without NaCl, producing a soil extract EC of 16 ds m −1 was used as the salinity treatment, beginning at the stem elongating stage. Significant correlations observed between grain dry matter (DM) and some ionic traits indicate that, beside the adverse effects of the higher leaf Na concentration on grain DM, the processes involved in the rate and/or duration of grain filling may be more efficient in terms of salt tolerance where grain yield is concerned. This may allow for the reproductive phase of growth to be salt tolerant independently of the vegetative one. Cultivar Inia-66 could serve as an example of this, showing higher rates of salt tolerance through the more suitable DM partitioning pattern. Mean comparisons made between the cultivars showed that the salt tolerant Roshan cultivar and, 10 other following cultivars, had the highest rates of absolute salt tolerance. This cultivar had the lowest leaf Na concentration, the highest K versus Na selectivity in ion transport from the soil to the grains, and also the highest grain K/Na ratios. It produced grain DM 7.5 times higher than the salt sensitive Ghods cultivar that had the lowest grain DM. The former 11 cultivars could therefore be considered as the most completely salt tolerant cultivars. In the cultivar Kharchia, salinity did not reduce the grain K/Na ratio and ion selectivity, but its grain filling period and HI were reduced under saline conditions.

Response of Wheat Cultivars to Varying Seeding Rates under Rainfed Conditions

Response of Wheat Cultivars to Varying Seeding Rates under Rainfed Conditions

Response of wheat cultivars to infection by Stagonospora nodorum isolates/mixture on detached and intact seedling leaves

Stagonospora nodorum blotch (SNB) of wheat caused by Stagonospora nodorum (Berk.) Castellani & E.G. Germano is among the major foliar diseases of wheat worldwide. The response of four wheat cultivars for reaction to infection by isolates/mixture of S. nodorum was tested on detached and intact seedling leaves in the laboratory and glasshouse experiments, respectively. The four wheat cultivars tested significantly differed from each other in response to infection by the isolates/mixture of S. nodorum. Similarly, the aggressiveness of the four isolates/mixture of the pathogen on the four wheat cultivars was significantly different as demonstrated by the parameters tested in the two experiments. However, no significant (p ≤ 0.05) isolate x cultivar interaction was observed for all the parameters tested in the two experiments. Highly significant positive or negative correlations were observed between parameters, i.e., disease severity (DS), incubation period(IP), and size of necrotic lesions (SNL), tested on detached and intact seedling leaves, respectively. This suggests that use of the detached leaf technique has considerable promise for quick screening of wheat cultivars against SNB.

Differential Response of Wheat Cultivars to Phosphorus Supply under Saline Conditions

Differential Response of Wheat Cultivars to Phosphorus Supply under Saline Conditions

Physiological attributes associated with early-season drought resistance in spring durum wheat cultivars

One of the common features of the Mediterranean climate in North Africa is the uncertainty of rainfall immediately after wheat (Triticum durum Desf) emerges. Relatively little work has been done to compare the drought resistance of spring durum wheat cultivars under early-season drought stress. There is a limited insight into the physiological basis of spring durum wheat drought resistance in rainfed Mediterranean regions. Field experiments were conducted in 1995 and 1996 growing seasons, and a greenhouse experiment was conducted in 1996 to examine differences in some physiological characters among six spring durum wheat cultivars in response to different durations of early-season drought, and rewatering; and to determine the relationships of these characters to drought resistance. Six spring durum wheat cultivars were evaluated under four water regimes. Water regime treatments were: a well-irrigated treatment; and three water deficit treatments imposed during the period from emergence through either the onset of tillering, mid-tillering or the end of tillering. Cultivars differed widely in their response to early season water stress. Under drought stress conditions, grain yield, aboveground dry matter yield, water use efficiency for the grain (WUEg) and for the total dry matter (WUEdm) were strongly positively associated with net CO2 uptake:transpiration ratio (A/E), and osmoregulation capacity. It is concluded that drought-induced changes in A, A/E, stomatal resistance, and osmotic adjustment are possible key control points in determining the drought-resistance of a cultivar. Furthermore, there is a substantial degree of intraspecific variation for the above mentioned physiological attributes to explore as a selection tool. Selection for high osmoregulation capacity and high A/E ratio would seem to be a justifiable means of improving total dry matter and grain yield under conditions of early-season water stress. Key words: Wheat, Triticum durum Desf., physiological attributes, early-season drought

Physiological Responses of Spring Durum Wheat Cultivars to Early-season Drought in a Mediterranean Environment

The Mediterranean climate of North Africa is characterized by uncertain rainfall immediately after seedling emergence, leading to drought early in the growing season which depresses durum wheat production. However, there is limited understanding of the physiological basis of resistance of spring durum wheat to drought in rainfed Mediterranean regions. The objectives of this study were to examine differences in some physiological characters among spring durum wheat cultivars in response to duration of early-season drought, and to determine the relationship of these characters to drought resistance. In two field experiments (1995 and 1996 growing seasons) and a glasshouse experiment (1996), six spring sown durum wheat cultivars were evaluated under four water regimes: well irrigated and three different water deficits from emergence until the onset of tillering, mid-tillering or at the end of tillering. Cultivars differed in their response. Decreases in photosynthesis soon after drought stress was imposed resulted mainly from reduced stomatal conductance. Continued water deficits also reduced mesophyll photosynthetic activity. Possible factors determining the drought-resistance of a cultivar are lower sensitivity of CO2exchange rate, net CO2uptake to water loss ratio, stomatal resistance, relative water content and greater osmotic adjustment under stress. Furthermore, there is sufficient intraspecific variation in these physiological attributes to suggest their use as selection tools.

Response of wheat cultivars to different soil nitrogen and moisture regimes: III. Leaf water content, conductance, and photosynthesis1

Abstract Two greenhouse studies were conducted with contrasting patterns of soil water availability and nitrogen (N) supply to extend our knowledge of the combined effect of these environmental factors on cultivar response of wheat (Triticum aestivum L.). Several parameters of water relations and photosynthesis were measured. Results showed that at the beginning of stem elongation and before imposing water stress, the low N treatment decreased leaf conductance and carbon dioxide (CO2) exchange rate (CER). This effect was more significant in the case of the cultivar Nesma than the other cultivars. Leaf conductance was a much better indicator of CER than chlorophyll content. Overall, water stress decreased leaf conductance. Under mild stress, Nesma and Merchouch 8 behaved similarly, but Nesma was more sensitive to water stress. Increased N decreased CER under water stress but tended to have no effect on chlorophyll concentration. Under well watered conditions, N application helped the plants maintain greate...

Responses of wheat cultivars to time of sowing in the southern wheatbelt of Western Australia

Experiments were conducted at 4 locations on an east-west transect in the 300-500 mm average annual rainfall zone in the southern wheatbelt of Western Australia, to determine whether promising crossbreds differ from existing wheat cultivars in their response to time of sowing. Nine cultivars and 2 crossbreds were examined at 3 sowing dates each year, ranging from late April to early July 1989, 1990, and 1991. Grain yield, grain quality (protein, hectolitre weight, grain weight, small grain sievings), crop development, and soil and weather variables were measured. The average decrease in grain yield with delay in sowing after early May was 20 kg/ha.day. All existing wheat cultivars and new crossbreds examined produced their highest yields when sown in early May. Yield decline for the crossbreds and cultivars was almost linear after early May; however, the rate of decline could not be entirely predicted from a knowledge of the crossbreds' maturities. Spear, the cultivar with longest maturity, was one of the highest yielding cultivars when sown in early May or June. The yields of the 2 shortest season cultivars, Kulin and Gutha, were only comparable to the yield of Spear when sown in June. Therefore, in the southern wheatbelt of Western Australia, we do not advise retaining a number of cultivars to suit a range of sowing times. The optimum flowering periods over the 3 seasons were 17 September-7 October in the medium rainfall zone of the southern wheatbelt and 3 September- 23 September in the low rainfall area at the most easterly location, reflecting the importance of terminal drought. There is still a risk of frost damage to wheat crops in about 1 year in 3 for the periods estimated. Therefore some risk of yield loss from frost damage must be accepted if yields are to be maximised.

The mechanism of differential response of wheat cultivars to chlorsulfuron

Summary: Résumé: ZusammenfassungWheat (Triticum aestivum L.) cultivars showed differential tolerance to chlorsulfuron. Cultivar Kotare showed no injury symptoms following foliar applications of chlorsulfuron at 15 or 60 g a.i. ha−1, while cultivars Rongotea and Lancer showed early damage in pot and field experiments at both rates of chlorsulfuron. Cultivars Abele and Jasper were intermediate in their response. The number of spikelets per ear was the only yield component affected by chlorsulfuron and was reduced in Lancer and Rongotea. Retention, uptake and transiocation of chlorsulfuron were not different between Kotare and Ron‐gotea. Within 48 h of application, Kotare metabolized 92–2% of [14C]chlorsulfuron, while Lancer and Rongotea metabolized only 43–5% and 63% of the herbicide, respectively. The concentration of chlorsulfuron in young tissues of Kotare, Lancer and Rongotea, 48 h after application was calculated as 1.2, 31.9 and 15.6 ng g−1 dry weight, respectively. It is concluded that differential rates of metabolism are the main reason for differences in sensitivity to chlorsulfuron between the wheat cultivars tested. Le mécanisme des différences de tolérance au chlorsulfuron entre variétés de blé Des variétés de blé (Triticum aestivum L.) ont montré des différences de tolérance au chlorsul‐furon. On n'a aucun symptôme de phytotoxicité sur la variété‘Kotare’ après une application foliaire de chlorsulfuron à 15 ou 60 g m.a. ha−1, alors que les variétés ‘Rongotea’ et ‘Lancer’ présentaient des symptômes précoces aux deux doses, dans des expériences en pot et au champ. La réponse des variété‘Abele’ et ‘Jasper’était intermédiaire. Le nombre de grains par épillet était la seule composante du rendement affectée parle chlorsulfuron et était réduit chez Lancer et Rongotea. La rétention, la pénétration et la migration de chlorsulfuron n'était pas différentes entre Kotare et Rongotea. Quarante huit heures après le traitement, Kotare avait metabolise 92,2% du [14C]chlorsulfuron, alors que Lancer et Rongotea ne métabolisaient que respectivement 43,5 et 63% de l'herbicide. La concentration de chlorsulfuron dans les tissus jeunes de Kotare, Lancer et Rongotea 48 h après la traitement a étéévaluée à respectivement 1,2,31,9 et 15,6 ng g−1 de matière sèche. Il est conclu que des différences de vitesse de métabolisation sont la raison principale des différences de sensibilité au chlorsulfuron observées chez les variétés de blé testées. Mechanismen der unterschiedlichen Reaktion von Weizensorten auf Chlorsulfuron‐Behandlun‐gen Es wurde eine unterschiedliche Toleranz bei Weizensorten (Triticum aestivum L.) gegenüber Chlorsulfuron‐Behandlungen beobachtet. Bei der Sorte ‘Kotare’ traten nach Behandlungen mit 15 oder 60 g AS ha keine Schadsymtome auf, während die Sorten ‘Rongotea’ und ‘Lancer’ sowohl in Topfals auch in Freilandversuchen bei beiden Dosen frühe Schädigungen erlitten; die Sorten ‘Abel’ und ‘Jasper’ reagierten mittelstark. Unter den Ertragskomponenten war nur die Zahl der Ährchen pro Ähre betroffen, sie war bei ‘Lancer’ und ‘Rongotea’ reduziert. Aufnahme und Translokation des Wirkstoffs waren bei ‘Kotare’ und ‘Rongotea’ gleich. Bei ‘Kotare’ war [14C]Chlorsulfuron 48 h nach der Applikation zu 92,2 % metabolisiert, bei ‘Rongotea’ zu 63 % und bei ‘Lancer’ zu 43,5 %. In jungen Geweben dieser Sorten lagen die Chlor‐sulfuron‐Konzentrationen 48 h nach der Anwendung bei 1,2, 15,6 und 31,9 ng g−1 TM. Die unterschiedlichen Metabolisierungsraten bei den untersuchten Weizensorten wurden für den Hauptgrund für die Toleranzunterschiede gegenüber Chlorsulfuron gehalten.

Response of wheat cultivars to different soil nitrogen and moisture regimes: I. Dry matter partitioning and root growth1

Abstract The balance between root and shoot growth is one of the mechanisms used by plants to adapt to a particular environment. This balance is affected by nutrient supply and water availability. The objective of this study was to understand how nitrogen (N) affects root and shoot growth of three cultivars of wheat (Triticum aestivum L.) grown under two regimes of soil moisture ('non water stressed’ and ‘stressed’ during stem elongation') in the greenhouse and growth chamber. Data showed that before stem elongation, shoot growth was less sensitive to high soil N levels than root growth. In fact, root growth was inhibited by excessive soil N concentration. The cultivar ‘Nesma’ produced more dry matter, absorbed N more rapidly and avoided the negative effect of high soil N concentrations on root growth. ‘Merchouch 8’ produced less dry matter and tolerated more water stress, and appeared to require less water. Severe water stress masked the effect of N on root and shoot growth, and the negative effect of wa...

Response of wheat cultivars to different soil nitrogen and moisture regimes: II. Nitrogen up‐take, partitioning and influx1

Abstract Nitrogen (N) is one of the major mineral nutrients required for growth and development of plants. Soil water availability, N concentration at the root surface and the ability of plants to absorb N are the most important factors that affect N uptake and partitioning. The objective of this study was to use greenhouse and growth chamber environments to investigate how two contrasting water regimes (stress and nonstress) and different soil N concentrations affect the uptake and distribution of N among different plant parts of three cultivars of wheat (Triticum aestivum L.) at different stages of development Results showed that at the beginning of stem elongation and under non N limiting conditions, there was a high and positive correlation between shoot dry matter production and shoot N content. Under N deficient soils that received different N rates, shoot N content was more related to shoot N concentration than to dry matter. Root growth and N content of the ‘Saada’ cultivar were negatively affecte...

Wheat growth responses of cultivars to H+ concentration

Shoot length (cm), shoot fresh weight (g/pot), root length (cm), and root fresh weight (g/pot) were measured on six cultivars of wheat (Triticum aestivum L. cv Saluda, C9733, Gore, Stacy, FL301, and FL302) grown at pH 6.0, 5.5, 5.0, 4.5, or 4.0 for 14 days in ‘white quartz flintshot’ sand. Plants were watered on alternate days with pH-adjusted buffer solutions. All measured plant parameters decreased as H+ concentration increased from pH 6.0 to 4.0. Decreased lengths of shoots and roots were similar among the cultivars as the pH decreased. This indicated a uniform response of wheat cultivars to excess H+ concentration in the soil solution; however, the decrease in shoot and root length was only about 50% as large as was previously reported for sorghum [Sorghum bicolor (L.) Moench.].

Effects of alien cytoplasm substitution on the response of wheat cultivars to Septoria nodorum

SUMMARYThe effects of alien cytoplasm substitution on the response of wheat to Septoria nodorum were studied, using alloplasmic series of two cultivars, Chris and Selkirk. In general, cytoplasmic substitution caused unidirectional effects on Septoria‐response, alloplasmic lines of both cultivars expressing lower levels of partial resistance (in leaf and head tissue) but higher levels of yield tolerance than the corresponding euplasmic line. The reduced resistance in alloplasmics was closely associated with reduced incubation periods of Septoria infection in both leaf and head tissue. Cytoplasmic substitution resulted in increased yield tolerance to Septoria‐infection in both the non‐tolerant Selkirk and the relatively tolerant Chris. Unlike their effects on partial resistance, specific cytoplasms exerted similar effects on tolerance in the two parental cultivars, several cytoplasms of the D plasmatype being particularly effective in increasing Septoria‐tolevance. The potential for the development of Septoria‐toterant cultivars by the incorporation of alien cytoplasms is discussed, in view of the observed neutral effects of D plasmatype cytoplasms on other agronomic traits.

Sink Manipulation in Wheat: Compensatory Changes in Kernel Size

Kernel size (KS), an important yield component of wheat (Triticum aestivum L.), depends on assimilate availability and the capacity of the kernel to use assimilates. The objective of this study was to evaluate the response of wheat cultivars with different KS (20 to 43 mg kernel −1,) to sink manipulation. Twenty cultivars grown at two locations were partially degrained by removal of all spikelets from one side of only one spike per plant. Control spikes were left intact. Partial degraining decreased kernel number (KN) by 51%. Relative compensatory kernel growth tended to increase with decreasing KS. However, the KS of five cultivars was unaffected by partial degraining, and the relative growth response of one small‐ and one large‐kernel cultivar each deviated markedly from the predicted response. Partial degralning enhanced kernel N of all cultivars, with an estimated 19 to 80% of the increase in KS attributed to greater accumulation of N compounds. For selected caltivars, the KS distribution and flag‐leaf abscisic acid (ABA) were determined to evaluate the relationship of sink size to these traits. Partial degraining altered KS distributions; for all but one of seven cultivars evaluated, partially degrained cultivars had the largest 5% of kernels and the single largest kernel. Compensatory kernel growth was unrelated to flag‐leaf ABA, indicating partial degraining had no adverse effects on assimilate supply related to excessive ABA levels in the flag leaf. These results demonstrate variable cultivar response to partial degraining; apparently, kernel growth of some cultivars is source limited, while other cultivars are at their capacity to accumulate assimilates.

Differential response of wheat cultivars to chlorsulfuron

Differential response of wheat cultivars to chlorsulfuron

Response of wheat cultivars to early post-emergence herbicides containing MCPA (2-methyl-4-chlorophenoxyacetic acid)

In southern New South Wales in 1978 and 1979, the responses of 10 spring wheat cultivars to early post-emergence applications of MCPA, bromoxynil plus MCPA, and dicamba plus MCPA, were evaluated. The herbicides were applied at the rate recommended by their manufacturer (1x), and at 3 times this rate (3x). Cultivars differed in their responses to these treatments and herbicide tolerance was related to the stage of development of the apical meristem of the main tiller at the time of spraying. Olympic, Shortim and Egret were the most sensitive cultivars and their grain yield, averaged over rate and year, was reduced by 33, 19, and 15% respectively. Songlen, Jabiru and Durati were the most tolerant cultivars. Songlen was not affected by any herbicide, even when the 3x rates were used, while the grain yields of Jabiru and Durati were only reduced in 1 year, and then only by the 3x rate of dicamba plus MCPA. The remaining cultivars, Kite, Gamenya, Condor and Lance, were intermediate in their response to these herbicide treatments. Delaying the application of 1 of these herbicides, dicamba plus MCPA, until spikelet initiation, minimised yield reductions. Correlations between visual assessment of crop damage and grain yield reduction varied between cultivars and between herbicides.

An Automated System for Harvesting Wheat Cultivars Grown under a Line Source Sprinkler Irrigation System1

AbstractThe purpose of this study was to design a fast and accurate method of harvesting cultivars and experimental lines of wheat grown under a line source sprinkler irrigation system. The harvesting system consisted of a strain gauge transducer energized with an amplifier‐indicator mounted on a Hege combine and a millivolt recorder and Omnidata Polycorder (use of trade names does not imply endorsement). Both methods of monitoring the voltage output from the transducer were adequately sensitive to allow continuous harvest and recording of yields at different distances from the line source sprinkler. Use of the polycorder was preferable to the millivolt recorder because data were more rapidly and accurately translated for computer‐assisted statistical analyses. This method will make it possible to quickly measure and compare the differential response of wheat cultivars and experimental lines to moisture stress.